Some Male Spiders Would Rather Eat Old Females Than Mate With Them Say Scientists

Black Widow female spiders sometimes eat their male suitors after mating. A new study has shown that the situation is reversed in some spider species. Some male spiders prefer to eat older female spiders instead of mating with them. The study by Lenka Sentenska and Stano Pekar from Masaryk University in the Czech Republic found that male spiders of the Micaria sociabilis species are more likely to eat the females than be eaten. The paper was published here in Springer's journal Behavioral Ecology and Sociobiology.

The researchers collected male and female Micaria sociabilis spiders over a two-year period and studied their behavior by mixing males and females of the species at different time points. All spiders were well fed to discount cannibalism due to hunger. The authors observed what happened when they paired young adult male spiders with young or old female spiders.

The authors found that the highest frequency of reverse cannibalism occurred when large, young males from the summer generation met old females from the previous spring generation. This suggests they may have based their choice on female age.

The scientists say in a statement, "Our study provides an insight into an unusual mating system, which differs significantly from the general model. Even males may choose their potential partners and apparently, in some cases, they can present their choice as extremely as females do by cannibalizing unpreferred mates."